Crystal structure, optical behavior and electrical conduction of the new organic–inorganic compound CH 3 NH 3 CdI 3

A new organic–inorganic compound CH3NH3CdI3 (MACdI3) was prepared by solvent diffusion method. Single crystal diffraction results showed that MACdI3 had a monoclinic system with P21/c space group at room temperature. UV–Visible absorption spectra revealed that the optical band gap (\({E_g}\)) of 3.45 eV is in agreement with the theoretical value. Band structure and density of states calculations indicated that the valence band is mainly iodine 5p in character and the conduction band is the interaction between Cd 4d in character and iodine 5p states. The temperature dependent dielectric constant and alternating current (AC) conduction analysis displayed a phase transition at about 348 K, which could be confirmed by temperature dependent Raman spectra. AC conduction results demonstrated that the conduction in MACdI3 was attributed to correlated barrier hopping at 308–348 K and non-overlapping small polaron tunneling at 348–398 K.